Systems and methods for a data scrambling procedure

ABSTRACT

Systems, methods, and devices for communicating in a wireless network are provided. In one aspect, a method for wireless communication is provided. The method includes inserting a plurality of scrambler seeds into a data unit comprising a plurality of data portions, each scrambler seed associated with a respective data portion of the plurality of data portions. The method includes scrambling each data portion at least in part based on the associated scrambler seed. The method includes transmitting the data unit. The data portions may comprise code words or at least one media access control protocol data unit. The scrambler seed may be inserted in reserved bits of the delimiter field. The scrambler seed may be inserted in a delimiter signature field of the delimiter field.

CLAIM OF PRIORITY UNDER 35 U.S.C. §119

The present Application for Patent claims priority to ProvisionalApplication No. 61/846,580 entitled “SYSTEMS AND METHODS FOR SCRAMBLINGPROCEDURE” filed Jul. 15, 2013, and assigned to the assignee hereof.Provisional Application No. 61/846,580 is hereby expressly incorporatedby reference herein.

BACKGROUND

Field

The present application relates generally to wireless communications,and more specifically to systems, methods, and devices for scramblinginformation transmitted in accordance with wireless communicationprotocols, such as members of the IEEE 802.11 family of wirelessprotocols.

Background

In many telecommunication systems, communications networks are used toexchange messages among several interacting spatially-separated devices.Networks may be classified according to geographic scope, which couldbe, for example, a metropolitan area, a local area, or a personal area.Such networks would be designated respectively as a wide area network(WAN), metropolitan area network (MAN), local area network (LAN), orpersonal area network (PAN). Networks also differ according to theswitching/routing technique used to interconnect the various networknodes and devices (e.g. circuit switching vs. packet switching), thetype of physical media employed for transmission (e.g. wired vs.wireless), and the set of communication protocols used (e.g. Internetprotocol suite, SONET (Synchronous Optical Networking), Ethernet, etc.).

Wireless networks are often preferred when the network elements aremobile and thus have dynamic connectivity needs, or if the networkarchitecture is formed in an ad hoc, rather than fixed, topology.Wireless networks employ intangible physical media in an unguidedpropagation mode using electromagnetic waves in the radio, microwave,infra-red, optical, etc. frequency bands. Wireless networksadvantageously facilitate user mobility and rapid field deployment whencompared to fixed wired networks.

The devices in a wireless network may transmit/receive informationbetween each other. The information may comprise packets, which in someaspects may be referred to as data units. The packets may includeoverhead information (e.g., header information, packet properties, etc.)that helps in routing the packet through the network, identifying thedata in the packet, processing the packet, etc., as well as data, forexample user data, multimedia content, etc. as might be carried in apayload of the packet.

SUMMARY

The systems, methods, and devices of the invention each have severalaspects, no single one of which is solely responsible for its desirableattributes. Without limiting the scope of this invention as expressed bythe claims which follow, some features will now be discussed briefly.After considering this discussion, and particularly after reading thesection entitled “Detailed Description” one will understand how thefeatures of this invention provide advantages.

In some implementations, a method for wireless communication isprovided. The method includes inserting an indication of a scramblingsequence into a signal field of a first data unit. The signal fieldoccurs before a service field of the first data unit. The method furthercomprises scrambling at least a portion of the first data unit based atleast on the inserted indication of the scrambling sequence in thesignal field of the first data unit. The method further comprisestransmitting the first data unit, the signal field being transmitted ata first data rate and the service field being transmitted at a seconddata rate greater than the first data rate.

In some other implementations, an apparatus for wireless communicationis provided. The apparatus comprises a processor configured to insert anindication of a scrambling sequence into a signal field of a first dataunit. The signal field occurs before a service field in the first dataunit. The processor is further configured to scramble at least a portionof the first data unit based at least on the inserted indication of thescrambling sequence in the signal field of the first data unit. Theapparatus further comprises a transmitter configured to transmit thefirst data unit, the signal field being transmitted at a first data rateand the service field being transmitted at a second data rate greaterthan the first data rate.

In some other implementations, a method for wireless communication isprovided. The method comprises receiving a first data unit comprising asignal field received at a first data rate and a service field receivedat a second data rate greater than the first data rate. The signal fieldis received before the service field in the first data unit. The methodcomprises descrambling at least a portion of the first data unit basedat least on an indication of a scrambling sequence inserted in thesignal field of the first data unit.

In some other implementations, an apparatus for wireless communicationis provided. The apparatus comprises a receiver configured to receive afirst data unit comprising a signal field and a service field. Thereceiver is configured to receive the signal field at a first data ratebefore receiving the service field at a second data rate greater thanthe first data rate. The apparatus comprises a processor configured todescramble at least a portion of the first data unit based at least onan indication of a scrambling sequence inserted in the signal field ofthe first data unit.

In some other implementations, a method for wireless communication isprovided. The method comprises inserting a plurality of scrambler seedsinto a data unit comprising a plurality of data portions, each scramblerseed associated with a respective data portion of the plurality of dataportions. The method comprises scrambling each data portion at least inpart based on the associated scrambler seed. The method comprisestransmitting the data unit.

In some other implementations, an apparatus for wireless communicationis provided. The apparatus comprises a processor configured to insert aplurality of scrambler seeds into a data unit comprising a plurality ofdata portions, each scrambler seed associated with a respective dataportion of the plurality of data portions. The processor is configuredto scramble each data portion at least in part based on the associatedscrambler seed. The apparatus comprises a transmitter configured totransmit the data unit.

In some other implementations, a method for wireless communication isprovided. The method comprises receiving a data unit comprising aplurality of data portions. The method comprises identifying a pluralityof scrambler seeds in the data unit, each scrambler seed associated witha respective data portion of the plurality of data portions. The methodcomprises descrambling each data portion at least in part based on theassociated scrambler seed.

In some other implementations, an apparatus for wireless communicationis provided. The apparatus comprises a receiver configured to receive adata unit comprising a plurality of data portions. The apparatuscomprises a processor configured to identify a plurality of scramblerseeds in the data unit, each scrambler seed associated with a respectivedata portion of the plurality of data portions. The processor isconfigured to descramble each data portion based at least in part on theassociated scrambler seed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example of a wireless communication system inwhich aspects of the present disclosure may be employed.

FIG. 2 shows a functional block diagram of an exemplary wireless devicethat may be employed within the wireless communication system of FIG. 1.

FIG. 3 shows a functional block diagram of exemplary components that maybe utilized in the wireless device of FIG. 2 to transmit wirelesscommunications.

FIG. 4 shows a functional block diagram of exemplary components that maybe utilized in the wireless device of FIG. 2 to receive wirelesscommunications.

FIG. 5A shows a functional block diagram for scrambling data beforeencoding the data, in accordance with at least some of the IEEE 802.11family of wireless protocols.

FIG. 5B shows a functional block diagram for encoding data beforescrambling the data, as may be employed within the wireless device ofFIG. 2.

FIG. 5C shows another functional block diagram of exemplary componentsthat may be employed in the wireless device of FIG. 2.

FIG. 5D shows another functional block diagram of exemplary componentsthat may be employed in the wireless device of FIG. 2.

FIG. 6A illustrates an example of a data unit or wireless frame.

FIG. 6B illustrates a data unit or wireless frame, in accordance withsome implementations.

FIG. 6C shows a data unit or wireless frame, in accordance with someimplementations.

FIG. 7A shows an exemplary structure of a media access control protocoldata unit (MPDU) frame.

FIG. 7B shows an exemplary implementation of a media access controlprotocol data unit (MPDU) frame containing a scrambler seed.

FIG. 8A shows an exemplary structure of an aggregated MPDU (A-MPDU)frame.

FIG. 8B shows an exemplary implementation of an MPDU delimiter fieldincluding a scrambler seed.

FIG. 8C shows another exemplary implementation of an MPDU delimiterfield including a scrambler seed.

FIG. 9 shows a flow chart of an exemplary method that may be employedwithin the wireless communication system of FIG. 1.

FIG. 10 shows a flow chart of another exemplary method that may beemployed within the wireless device of FIG. 2.

FIG. 11 shows a flow chart of yet another exemplary method that may beemployed within the wireless device of FIG. 2.

FIG. 12 shows a flow chart of yet another exemplary method that may beemployed within the wireless device of FIG. 2.

FIG. 13 shows a flow chart of yet another exemplary method that may beemployed within the wireless device of FIG. 2.

FIG. 14 shows a flow chart of yet another exemplary method that may beemployed within the wireless device of FIG. 2.

FIG. 15 shows a flow chart of yet another exemplary method that may beemployed within the wireless device of FIG. 2.

FIG. 16 shows a flow chart of yet another exemplary method that may beemployed within the wireless device of FIG. 2.

FIG. 17 shows a flow chart of yet another exemplary method that may beemployed within the wireless device of FIG. 2.

FIG. 18 shows a flow chart of yet another exemplary method that may beemployed within the wireless device of FIG. 2.

FIG. 19 shows a flow chart of yet another exemplary method that may beemployed within the wireless device of FIG. 2.

FIG. 20 shows a flow chart of yet another exemplary method that may beemployed within the wireless device of FIG. 2.

FIG. 21 shows a flow chart of yet another exemplary method that may beemployed within the wireless device of FIG. 2.

DETAILED DESCRIPTION

Various aspects of the novel systems, apparatuses, and methods aredescribed more fully hereinafter with reference to the accompanyingdrawings. The teachings disclosure may, however, be embodied in manydifferent forms and should not be construed as limited to any specificstructure or function presented throughout this disclosure. Rather,these aspects are provided so that this disclosure will be thorough andcomplete, and will fully convey the scope of the disclosure to thoseskilled in the art. Based on the teachings herein one skilled in the artshould appreciate that the scope of the disclosure is intended to coverany aspect of the novel systems, apparatuses, and methods disclosedherein, whether implemented independently of or combined with any otheraspect of the invention. For example, an apparatus may be implemented ora method may be practiced using any number of the aspects set forthherein. In addition, the scope of the invention is intended to coversuch an apparatus or method which is practiced using other structure,functionality, or structure and functionality in addition to or otherthan the various aspects of the invention set forth herein. It should beunderstood that any aspect disclosed herein may be embodied by one ormore elements of a claim.

Although particular aspects are described herein, many variations andpermutations of these aspects fall within the scope of the disclosure.Although some benefits and advantages of the preferred aspects arementioned, the scope of the disclosure is not intended to be limited toparticular benefits, uses, or objectives. Rather, aspects of thedisclosure are intended to be broadly applicable to different wirelesstechnologies, system configurations, networks, and transmissionprotocols, some of which are illustrated by way of example in thefigures and in the following description of the preferred aspects. Thedetailed description and drawings are merely illustrative of thedisclosure rather than limiting, the scope of the disclosure beingdefined by the appended claims and equivalents thereof.

Wireless network technologies may include various types of wirelesslocal area networks (WLANs). A WLAN may be used to interconnect nearbydevices together, employing widely used networking protocols. Thevarious aspects described herein may apply to any communicationstandard, such as WiFi or, more generally, any member of the IEEE 802.11family of wireless protocols. For example, the various aspects describedherein may be used as part of the IEEE 802.11ah protocol, which usessub-1 GHz bands.

In some aspects, wireless signals in a sub-gigahertz band may betransmitted according to the 802.11ah protocol using orthogonalfrequency-division multiplexing (OFDM), direct-sequence spread spectrum(DSSS) communications, a combination of OFDM and DSSS communications, orother schemes. Implementations of the 802.11ah protocol may be used forsensors, metering, and smart grid networks. Advantageously, aspects ofcertain devices implementing the 802.11ah protocol may consume lesspower than devices implementing other wireless protocols, and/or may beused to transmit wireless signals across a relatively long range, forexample about one kilometer or longer.

In some implementations, a WLAN includes various devices which are thecomponents that access the wireless network. For example, there may betwo types of devices: access points (“APs”) and clients (also referredto as stations, or “STAs”). In general, an AP serves as a hub or basestation for the WLAN and a STA serves as a user of the WLAN. Forexample, an STA may be a laptop computer, a personal digital assistant(PDA), a mobile phone, etc. In an example, an STA connects to an AP viaa WiFi (e.g., IEEE 802.11 protocol such as 802.11ah) compliant wirelesslink to obtain general connectivity to the Internet or to other widearea networks. In some implementations, an STA may also be used as anAP.

An access point (“AP”) may also comprise, be implemented as, or known asa NodeB, Radio Network Controller (“RNC”), eNodeB, Base StationController (“BSC”), Base Transceiver Station (“BTS”), Base Station(“BS”), Transceiver Function (“TF”), Radio Router, Radio Transceiver, orsome other terminology.

A station “STA” may also comprise, be implemented as, or known as anaccess terminal (“AT”), a subscriber station, a subscriber unit, amobile station, a remote station, a remote terminal, a user terminal, auser agent, a user device, user equipment, or some other terminology. Insome implementations, an access terminal may comprise a cellulartelephone, a cordless telephone, a Session Initiation Protocol (“SIP”)phone, a wireless local loop (“WLL”) station, a personal digitalassistant (“PDA”), a handheld device having wireless connectioncapability, or some other suitable processing device connected to awireless modem. Accordingly, one or more aspects taught herein may beincorporated into a phone (e.g., a cellular phone or smartphone), acomputer (e.g., a laptop), a portable communication device, a headset, aportable computing device (e.g., a personal data assistant), anentertainment device (e.g., a music or video device, or a satelliteradio), a gaming device or system, a global positioning system device,or any other suitable device that is configured to communicate via awireless medium.

As discussed above, certain of the devices described herein mayimplement the 802.11ah standard, for example. Such devices, whether usedas an STA or AP or other device, may be used for smart metering or in asmart grid network. Such devices may provide sensor applications or beused in home automation. The devices may instead or in addition be usedin a healthcare context, for example for personal healthcare. They mayalso be used for surveillance, to enable extended-range Internetconnectivity (e.g. for use with hotspots), or to implementmachine-to-machine communications.

The devices in a wireless network may transmit/receive informationbetween each other. The information may comprise packets, which in someaspects may be referred to as data units. The packets may includeoverhead information (e.g., header information, packet properties, etc.)that helps in routing the packet through the network, identifying thedata in the packet, processing the packet, etc., as well as data, forexample user data, multimedia content, etc. as might be carried in apayload of the packet.

FIG. 1 illustrates an example of a wireless communication system 100 inwhich aspects of the present disclosure may be employed. The wirelesscommunication system 100 may operate pursuant to a wireless standard,for example the 802.11ah standard. The wireless communication system 100may include an (access point) AP 104, which communicates with STAs 106.

A variety of processes and methods may be used for transmissions in thewireless communication system 100 between the AP 104 and the STAs 106.For example, signals may be sent and received between the AP 104 and theSTAs 106 in accordance with OFDM/OFDMA techniques. If this is the case,the wireless communication system 100 may be referred to as anOFDM/OFDMA system. Alternatively, signals may be sent and receivedbetween the AP 104 and the STAs 106 in accordance with CDMA techniques.If this is the case, the wireless communication system 100 may bereferred to as a CDMA system.

A communication link that facilitates transmission from the AP 104 toone or more of the STAs 106 may be referred to as a downlink (DL) 108,and a communication link that facilitates transmission from one or moreof the STAs 106 to the AP 104 may be referred to as an uplink (UL) 110.Alternatively, a downlink 108 may be referred to as a forward link or aforward channel, and an uplink 110 may be referred to as a reverse linkor a reverse channel.

The AP 104 may act as a base station and provide wireless communicationcoverage in a basic service area (BSA) 102. The AP 104 along with theSTAs 106 associated with the AP 104 that use the AP 104 forcommunication may be referred to as a basic service set (BSS). It shouldbe noted that the wireless communication system 100 may not have acentral AP 104, but rather may function as a peer-to-peer networkbetween the STAs 106. Accordingly, the functions of the AP 104 describedherein may alternatively be performed by one or more of the STAs 106.

In some implementations, the AP 104 and STAs 106 can implement anautomatic repeat request (ARQ) error-control procedure for datatransmission. ARQ can use acknowledgements (ACKs) and timeouts tofacilitate reliable data transmission. An ACK can include a message sentby a receiver indicating that it has correctly received a data frame orpacket. A timeout can include a period of time allowed to elapse beforea message is retransmitted. In other words, if a sender does not receivean ACK before the timeout, it can re-transmit the packet until thesender receives an ACK or exceeds a threshold number of retransmissions.In some implementations, the receiver discards packets that are notsuccessfully decoded.

In some implementations, the AP 104 and STAs 106 can implement a hybridARQ (HARQ) error-control procedure for data transmission. HARQ canfurther implement error-correction codes to facilitate reliable datatransmission. In various implementations, as used herein,error-correction codes can encompass any error-correction codesincluding, but not limited to, parity information, forwarderror-correction (FEC) codes, fountain codes, raptor codes, etc. In someimplementations, “Parity,” as used herein, refers to information thatallows error correction of, e.g., a data unit. In some implementationsdescribed herein, parity is computed based on a data unit referred to asa “primary data unit.” In these implementations, the term “primary” in“primary data unit” is used in order to express the relationship of the“primary data unit” to the “parity data unit.” In these implementations,the “parity data unit” allows error correction of the “primary dataunit.” In some implementations, FEC encoding may be done with lowdensity parity check (LDPC) codes.

In general, the HARQ protocol involves the receiver STA storinginformation regarding received code word signals when receiving a PPDU,even when those code words fail to decode correctly. The storedinformation can be decoded bits, original received data samples, bitlikelihood values, etc. depending on the HARQ combining method beingutilized, of which many are well known to those of skill in the art. Theidentity of failed code words is provided either explicitly orimplicitly back to the transmitter STA. In response to this information,the transmitter STA sends a new PPDU with additional parity informationand/or a retransmission of some of the previously transmitted bits. Theadditional parity information may be part or all of the originallypunctured parity bits, or may be a new parity portion computed with alower code rate. When received by the receiver STA, this newly receivedinformation is combined with the stored information to attempt again todecode the failed code word.

In some implementations, the sender can transmit additional packetsincluding additional error-correction codes, when an ACK is notreceived. The receiver can store packets that are unsuccessfully decodedfor later combination with additional packets including additionalerror-correction codes. Accordingly, the receiver can recoverunsuccessfully decoded packets by matching the packets with theadditional error-correction codes.

The STAs 106 are not limited in type and may include a variety ofdifferent STAs. For example, as illustrated in FIG. 1, STAs 106 caninclude a cellular phone 106 a, a television 106 b, a laptop 106 c, anda number of sensors 106 d-f (e.g. a weather sensor or other sensorcapable of communicating using a wireless protocol), to name a few.

FIG. 2 shows a functional block diagram of an exemplary wireless device202 that may be employed within the wireless communication system 100 ofFIG. 1. The wireless device 202 is an example of a device that may beconfigured to implement the various methods described herein. Forexample, the wireless device 202 may comprise the AP 104 or one of theSTAs 106.

The wireless device 202 may include a processor 204 which controlsoperation of the wireless device 202. The processor 204 may also bereferred to as a central processing unit (CPU). Memory 206, which mayinclude both read-only memory (ROM) and random access memory (RAM),provides instructions and data to the processor 204. A portion of thememory 206 may also include non-volatile random access memory (NVRAM).The processor 204 typically performs logical and arithmetic operationsbased on program instructions stored within the memory 206. Theinstructions in the memory 206 may be executable to implement themethods described herein.

The processor 204 may comprise or be a component of a processing systemimplemented with one or more processors. The one or more processors maybe implemented with any combination of general-purpose microprocessors,microcontrollers, digital signal processors (DSPs), field programmablegate array (FPGAs), programmable logic devices (PLDs), controllers,state machines, gated logic, discrete hardware components, dedicatedhardware finite state machines, or any other suitable entities that canperform calculations or other manipulations of information.

The processing system may also include machine-readable media forstoring software. Software shall be construed broadly to mean any typeof instructions, whether referred to as software, firmware, middleware,microcode, hardware description language, or otherwise. Instructions mayinclude code (e.g., in source code format, binary code format,executable code format, or any other suitable format of code). Theinstructions, when executed by the one or more processors, cause theprocessing system to perform the various functions described herein.

The wireless device 202 may also include a housing 208 that may includea transmitter 210 and a receiver 212 to allow transmission and receptionof data between the wireless device 202 and a remote location. Further,the transmitters 210 and the receiver 212 may be configured to allowtransmission and reception of setup and/or configuration packets orframes between the wireless device 202 and a remote location including,for example, an AP. The transmitter 210 and receiver 212 may be combinedinto a transceiver 214. An antenna 216 may be attached to the housing208 and electrically coupled to the transceiver 214. Alternatively, oradditionally, the wireless device 202 may include an antenna 216 formedas part of the housing 208 or may be an internal antenna. The wirelessdevice 202 may also include (not shown) multiple transmitters, multiplereceivers, multiple transceivers, and/or multiple antennas.

The wireless device 202 may also include a signal detector 218 that maybe used in an effort to detect and quantify the level of signalsreceived by the transceiver 214. The signal detector 218 may detect suchsignals as total energy, energy per subcarrier per symbol, powerspectral density and other signals. The wireless device 202 may alsoinclude a digital signal processor (DSP) 220 for use in processingsignals. The DSP 220 may be configured to generate a data unit fortransmission. In some aspects, the data unit may comprise a physicallayer data unit (PPDU). In some aspects, the PPDU is referred to as apacket or a frame.

In some implementations, the wireless device 202 may also include a SIGfield scrambler seed processor 230 for use in processing signals. TheSIG field scrambler seed processor 230 may be configured to generate adata unit for transmission. In some aspects, the data unit may comprisea physical layer data unit (PPDU). In some aspects, the PPDU is referredto as a packet or a frame. In some implementations, the SIG fieldscrambler seed processor 230 may insert a scrambler seed into the SIGfield of a data unit. In some implementations described herein, theterms “scrambler seed” and “descrambler seed” may be usedinterchangeably. In some implementations, the SIG field scrambler seedprocessor 230 may scramble the data unit based on a scrambler seedinserted into the SIG field of a data unit. The SIG field scrambler seedprocessor 230 may not be present in certain implementations. Moreover,as those having ordinary skill in the art will appreciate, SIG fieldscrambler seed processor 230 may not be present if other components ofwireless device 202 perform the operations described herein as performedby the SIG field scrambler seed processor 230. For example, processor204 or DSP 220 may be designed to perform these operations in certaincircumstances. Conversely, SIG field scrambler seed processor 230 may beable to perform functions described herein as performed by othercomponents of wireless device 202, such as processor 204 or DSP 220.

The wireless device 202 may further comprise a user interface 222 insome aspects. The user interface 222 may comprise a keypad, amicrophone, a speaker, and/or a display. The user interface 222 mayinclude any element or component that conveys information to a user ofthe wireless device 202 and/or receives input from the user.

The various components of the wireless device 202 may be housed within ahousing 208. Further, the various components of the wireless device 202may be coupled together by a bus system 226. The bus system 226 mayinclude a data bus, for example, as well as a power bus, a controlsignal bus, and a status signal bus in addition to the data bus. Thoseof skill in the art will appreciate the components of the wirelessdevice 202 may be coupled together, or may accept or provide inputs toeach other using some other mechanism.

Although a number of separate components are illustrated in FIG. 2,those of skill in the art will recognize that one or more of thecomponents may be combined or commonly implemented. For example, theprocessor 204 may be used to implement not only the functionalitydescribed above with respect to the processor 204, but also to implementthe functionality described above with respect to the signal detector218 and/or the DSP 220. Further, each of the components illustrated inFIG. 2 may be implemented using a plurality of separate elements.

In certain wireless communications such as those specified in the IEEE802.11ah protocol, a sub-gigahertz band may be used. This band may havea longer range than other higher bands, at the same transmission power.For example, these bands may have approximately twice the range of 2.4GHz or 5 GHz bands, as used in IEEE 802.11n. This longer range mayenable devices to communicate from a greater distance.

As discussed above, the wireless device 202 may comprise an AP 104 or anSTA 106, and may be used to transmit and/or receive communications.Although the wireless device 202 of FIG. 2 is illustrated as includingboth a transmitter 210 and a receiver 212, some exemplaryimplementations may include the transmitter 210 and not the receiver212, or in the alternative, the receiver 212 and not the transmitter210. Where the wireless device 202 includes the transmitter 210 and/orthe receiver 212, the wireless device 202 may additionally include oneor more of the functional blocks described below in connection withFIGS. 3 and/or 4, respectively.

FIG. 3 shows a functional block diagram of exemplary components that maybe utilized in the wireless device 202 of FIG. 2 to transmit wirelesscommunications. The components illustrated in FIG. 3 may be used, forexample, to transmit OFDM communications. The wireless device 202 maycomprise a modulator 302 configured to modulate bits for transmission.For example, the modulator 302 may determine a plurality of symbols frombits received from the processor 204 or the user interface 222, forexample by mapping bits to a plurality of symbols according to aconstellation. The bits may correspond to user data or to controlinformation. In some aspects, the bits are received in code words. Inone aspect, the modulator 302 comprises a QAM (quadrature amplitudemodulation) modulator, for example a 16-QAM modulator or a 64-QAMmodulator. In other aspects, the modulator 302 comprises a binaryphase-shift keying (BPSK) modulator or a quadrature phase-shift keying(QPSK) modulator.

The wireless device 202 may further comprise a transform module 304configured to convert symbols or otherwise modulated bits from themodulator 302 into a time domain. In FIG. 3, the transform module 304 isillustrated as being implemented by an inverse fast Fourier transform(IFFT) module. In some implementations, there may be multiple transformmodules (not shown) that transform units of data of different sizes.

In FIG. 3, the modulator 302 and the transform module 304 areillustrated as being implemented in the DSP 220. In some aspects,however, one or both of the modulator 302 and the transform module 304are implemented in the processor 204 or in another element of thewireless device 202.

As discussed above, the DSP 220 may be configured to generate a dataunit for transmission. In some aspects, the modulator 302 and thetransform module 304 may be configured to generate a data unitcomprising a plurality of fields including control information and aplurality of data symbols. The fields including the control informationmay comprise one or more training fields, for example, and one or moresignal (SIG) fields. Each of the training fields may include a knownsequence of bits or symbols. Each of the SIG fields may includeinformation about the data unit, for example a description of a lengthor data rate of the data unit.

Returning to the description of FIG. 3, the wireless device 202 mayfurther comprise a digital to analog converter (DAC) 306 configured toconvert the output of the transform module into an analog signal. Forexample, the time-domain output of the transform module 306 may beconverted to a baseband OFDM signal by the digital to analog converter306. The digital to analog converter 306 may be implemented in theprocessor 204 or in another element of the wireless device 202. In someaspects, the digital to analog converter 306 is implemented in thetransceiver 214 or in a data transmit processor.

The analog signal may be wirelessly transmitted by the transmitter 210.The analog signal may be further processed before being transmitted bythe transmitter 210, for example by being filtered or by beingupconverted to an intermediate or carrier frequency. In the aspectillustrated in FIG. 3, the transmitter 210 includes a transmit amplifier308. Prior to being transmitted, the analog signal may be amplified bythe transmit amplifier 308. In some aspects, the amplifier 308 comprisesa low noise amplifier (LNA).

The transmitter 210 is configured to transmit one or more packets ordata units in a wireless signal based on the analog signal. The dataunits may be generated using the processor 204 and/or the DSP 220, forexample using the modulator 302 and the transform module 304 asdiscussed above. Data units that may be generated and transmitted asdiscussed above are described in additional detail below.

FIG. 4 shows a functional block diagram of exemplary components that maybe utilized in the wireless device 202 of FIG. 2 to receive wirelesscommunications. The components illustrated in FIG. 4 may be used, forexample, to receive OFDM communications. In some aspects, the componentsillustrated in FIG. 4 are used to receive data units that include one ormore SIGNAL units, as will be discussed in additional detail below. Forexample, the components illustrated in FIG. 4 may be used to receivedata units transmitted by the components discussed above with respect toFIG. 3.

The receiver 212 is configured to receive one or more packets or dataunits in a wireless signal. Data units that may be received and decodedor otherwise processed as discussed below are described in additionaldetail with respect to FIGS. 5-9.

In the aspect illustrated in FIG. 4, the receiver 212 includes a receiveamplifier 401. The receive amplifier 401 may be configured to amplifythe wireless signal received by the receiver 212. In some aspects, thereceiver 212 is configured to adjust the gain of the receive amplifier401 using an automatic gain control (AGC) procedure. In some aspects,the automatic gain control uses information in one or more receivedtraining fields, such as a received short training field (STF) forexample, to adjust the gain. Those having ordinary skill in the art willunderstand methods for performing AGC. In some aspects, the amplifier401 comprises an LNA.

The wireless device 202 may comprise an analog to digital converter 402configured to convert the amplified wireless signal from the receiver212 into a digital representation thereof. Further to being amplified,the wireless signal may be processed before being converted by thedigital to analog converter 402, for example by being filtered or bybeing downconverted to an intermediate or baseband frequency. The analogto digital converter 402 may be implemented in the processor 204 or inanother element of the wireless device 202. In some aspects, the analogto digital converter 402 is implemented in the transceiver 214 or in adata receive processor.

The wireless device 202 may further comprise a transform module 404configured to convert the representation the wireless signal into afrequency spectrum. In FIG. 4, the transform module 404 is illustratedas being implemented by a fast Fourier transform (FFT) module. Thetransform module 404 may be programmable, and may be configured toperform FFT with different configurations. In one aspect, for example,the transform module 404 may be configured to perform either a 32-pointFFT or a 64-point FFT. In some aspects, the transform module mayidentify a symbol for each point that it uses.

The wireless device 202 may further comprise a channel estimator andequalizer 405 configured to form an estimate of the channel over whichthe data unit is received, and to remove certain effects of the channelbased on the channel estimate. For example, the channel estimator may beconfigured to approximate a function of the channel, and the channelequalizer may be configured to apply an inverse of that function to thedata in the frequency spectrum.

In some aspects, the channel estimator and equalizer 405 usesinformation in one or more received training fields, such as a longtraining field (LTF) for example, to estimate the channel. The channelestimate may be formed based on one or more LTFs received at thebeginning of the data unit. This channel estimate may thereafter be usedto equalize data symbols that follow the one or more LTFs. After acertain period of time or after a certain number of data symbols, one ormore additional LTFs may be received in the data unit. The channelestimate may be updated or a new estimate formed using the additionalLTFs. This new or update channel estimate may be used to equalize datasymbols that follow the additional LTFs. In some aspects, the new orupdated channel estimate is used to re-equalize data symbols precedingthe additional LTFs. Those having ordinary skill in the art willunderstand methods for forming a channel estimate.

The wireless device 202 may further comprise a demodulator 406configured to demodulate the equalized data. For example, thedemodulator 406 may determine a plurality of bits from symbols output bythe transform module 404 and the channel estimator and equalizer 405,for example by reversing a mapping of bits to a symbol in aconstellation. The bits may be processed or evaluated by the processor204, or used to display or otherwise output information to the userinterface 222. In this way, data and/or information may be decoded. Insome aspects, the bits correspond to code words. In one aspect, thedemodulator 406 comprises a QAM (quadrature amplitude modulation)demodulator, for example a 16-QAM demodulator or a 64-QAM demodulator.In other aspects, the demodulator 406 comprises a binary phase-shiftkeying (BPSK) demodulator or a quadrature phase-shift keying (QPSK)demodulator.

In FIG. 4, the transform module 404, the channel estimator and equalizer405, and the demodulator 406 are illustrated as being implemented in theDSP 220. In some aspects, however, one or more of the transform module404, the channel estimator and equalizer 405, and the demodulator 406are implemented in the processor 204 or in another element of thewireless device 202.

As discussed above, the wireless signal received at the receiver 212comprises one or more data units. Using the functions or componentsdescribed above, the data units or data symbols therein may be decodedevaluated or otherwise evaluated or processed. For example, theprocessor 204 and/or the DSP 220 may be used to decode data symbols inthe data units using the transform module 404, the channel estimator andequalizer 405, and the demodulator 406.

Data units exchanged by the AP 104 and the STA 106 may include controlinformation or data, as discussed above. At the physical (PHY) layer,these data units may be referred to as physical layer protocol dataunits (PPDUs). In some aspects, a PPDU may be referred to as a packet orphysical layer packet. Each PPDU may comprise a preamble and a payload.The preamble may include training fields and a SIG field. The payloadmay comprise a Media Access Control (MAC) header or data for otherlayers, and/or user data, for example. In various implementations, dataunits can include Mac Protocol Data Units (MPDU) and/or Aggregated MacProtocol Data Units (A-MPDU). The payload may be transmitted using oneor more data symbols. The systems, methods, and devices herein mayutilize data units with training fields whose peak-to-power ratio hasbeen minimized.

Certain implementations described herein may be directed to wirelesscommunication systems that may be used for smart metering or be used ina smart grid network. These wireless communication systems may be usedto provide sensor applications or be used in home automation. Wirelessdevices used in such systems may instead or in addition be used in ahealthcare context, for example, for personal healthcare. They may alsobe used for surveillance, to enable extended-range Internet connectivity(e.g., for use with hotspots), or to implement machine-to-machinecommunications. Accordingly, some implementations may use low data ratessuch as approximately 150 Kbps. Implementations may further haveincreased link budget gains (e.g., around 20 dB) over other wirelesscommunications such as 802.11b. In accordance with low data rates, ifwireless nodes are configured for use in a home environment, certainaspects may be directed to implementations with good in-home coveragewithout power amplification. Furthermore, certain aspects may bedirected to single-hop networking without using a MESH protocol. Inaddition, certain implementations may result in significant outdoorcoverage improvement with power amplification over other wirelessprotocols. Furthermore, certain aspects may be directed toimplementations that may accommodate large outdoor delay-spread andreduced sensitivity to Doppler. Certain implementations may achievesimilar LO accuracy as traditional WiFi.

Accordingly, certain implementations are directed to sending wirelesssignals with low bandwidths in sub-gigahertz bands. For example, in oneexemplary implementation, a symbol may be configured to be transmittedor received using a bandwidth of 1 MHz. The wireless device 202 of FIG.2 may be configured to operate in one of several modes. In one mode,symbols such as OFDM symbols may be transmitted or received using abandwidth of 1 MHz. In another mode, symbols may be transmitted orreceived using a bandwidth of 2 MHz. Additional modes may also beprovided for transmitting or receiving symbols using a bandwidth of 4MHz, 8 MHz, 16 MHz, 20 MHz, 40 MHz, 80 MHz, and the like. The bandwidthmay also be referred to as the channel width.

Each mode may use a different number of tones/subcarriers fortransmitting the information. For example, in one implementation, a 1MHz mode (corresponding to transmitting or receiving symbols using abandwidth of 1 MHz) may use 32 tones. In one aspect, using a 1 MHz modemay provide for a 13 dB noise reduction as compared to a bandwidth suchas 20 MHz. In addition, low rate techniques may be used to overcomeeffects such as frequency diversity losses due to a lower bandwidthwhich could result in 4-5 dB losses depending on channel conditions. Togenerate/evaluate symbols sent or received using 32 tones, a transformmodule 304 or 404 as described above with reference to FIGS. 3 and 4above may be configured to use a 32 point mode (e.g., a 32 point IFFT orFFT). The 32 tones may be allocated as data tones, pilot tones, guardtones, and a DC tone. In one implementation, 24 tones may be allocatedas data tones, 2 tones may be allocated as pilot tones, five tones maybe allocated as guard tones, and 1 tone may be reserved for the DC tone.In this implementation, the symbol duration may be configured to be 40μs including cyclic prefix. Other tone allocations are also possible.

For example, the wireless device 202 (FIGS. 2 and/or 3) may beconfigured to generate a packet for transmission via a wireless signalusing a bandwidth of 1 MHz. In one aspect, the bandwidth may beapproximately 1 MHz where approximately 1 MHz may be within a range of0.8 MHz to 1.2 MHz. The packet may be formed of one or more OFDM symbolshaving 32 tones allocated as described using a DSP 320 (FIG. 3) or otherprocessor as described above. A transform module 304 (FIG. 3) in atransmit chain may be configured as an IFFT module operating accordingto a thirty-two point mode to convert the packet into a time domainsignal. A transmitter 310 (FIG. 3) may then be configured to transmitthe packet.

Likewise, the wireless device 202 (FIGS. 2 and/or 4) may be configuredto receive the packet over a bandwidth of 1 MHz. In one aspect, thebandwidth may be approximately 1 MHz where approximately 1 MHz may bewithin a range of 0.8 MHz to 1.2 MHz. The wireless device 202 mayinclude a DSP 420 including a transform module 404 (FIG. 4) in a receivechain that may be configured as an FFT module operating according to athirty-two point mode to transform the time domain signal into afrequency spectrum. A DSP 420 may be configured to evaluate the packet.The 1 MHz mode may support a modulation and coding scheme (MCS) for botha low data rate and a “normal” rate. According to some implementations,the preamble 702 may be designed for a low rate mode that offersreliable detection and improved channel estimation as will be furtherdescribed below. Each mode may be configured to use a correspondingpreamble configured to optimize transmissions for the mode and desiredcharacteristics.

In addition to a 1 MHz mode, a 2 MHz mode may additionally be availablethat may be used to transmit and receive symbols using 64 tones. In oneimplementation, the 64 tones may be allocated as 52 data tones, 4 pilottones, 1 DC tone, and 7 guard tones. As such, a transform module 304 or404 of FIGS. 3 and 4 may be configured to operate according to a 64point mode when transmitting or receiving 2 MHz symbols. The symbolduration may also be 40 μs including cyclic prefix. Additional modeswith different bandwidths (e.g., 4 MHz, 8 MHz, and 16 MHz) may beprovided that may use transform modules 304 or 404 operating in modes ofcorresponding different sizes (e.g., 128 point FFT, 256 point FFT, 512point FFT, etc.). In addition, each of the modes described above may beconfigured additionally according to both a single user mode and a multiuser mode. Wireless signals using bandwidths less than or equal to 2 MHzmay provide various advantages for providing wireless nodes that areconfigured to meet global regulatory constraints over a broad range ofbandwidth, power, and channel limitations.

As described above, the wireless device 202 may comprise an AP 104 or aSTA 106, and may be used to transmit and/or receive media access control(MAC) frames of different types.

FIG. 5A shows a functional block diagram 500A for scrambling data beforeencoding the data, in accordance with at least some of the IEEE 802.11family of wireless protocols. In the functional block diagram 500A, dataunits may be scrambled by scrambler 510A prior to being encoded. Forexample, the scrambler 510A may scramble data received at an input ofthe scrambler 510A and output the scrambled data to an encoder parser512A. The encoder parser 512A may divide or demultiplex the scrambleddata among a plurality of forward error correction (FEC) encoders (e.g.,FEC encoders 514A and 514B). In some implementations, the encoder parser512A may divide or demultiplex the scrambled data in a round robinmanner. Each of the FEC encoders 514A/1514B may then encode the dividedor demultiplexed scrambled data and forward the encoded scrambled datato a stream parser 516A. The stream parser 516A may further divide ordemultiplex the encoded scrambled data among a plurality of interleavers(e.g., interleavers 518A, 518B, 518C and 518D). Each of the interleavers518A-518D may shuffle one or more symbols of the encoded scrambled dataamong a plurality of code words in order to improve FEC performance.Each of the interleavers 518A-518D may then output the interleavedencoded scrambled data to a respective constellation mapper (e.g.,constellation mappers 520A-520D, respectively). Each of theconstellation mappers 520A-520D may map received interleaved encodedscrambled data to corresponding signal constellations. The constellationmappers 520A-520D may then provide an output to a spatial time blockcoder 522A, which may provide spatial time block coding of the receivedmapped, interleaved encoded scrambled data. At least some of the outputsof the spatial time block coder 522A may be input to respective circuitswitches 524A, 524B, 524C, and then output to a spatial mapper 526A. Thespatial mapper 526A may then provide an output to each of a plurality ofinverse discrete fourier transformers (e.g., IDFTs 528A-528D). Each ofthe IDFTs 528A-528D may provide an output to a respective module forinserting at least a guard interval (GI) into the data (e.g., modules530A-530D). Each of the modules 530A-530D may then provide an output toa respective one of a plurality of digital to analog and radio frequencymodules (e.g., modules 532A-532D). Each of the modules 532A-532D mayconvert received signals from a digital to an analog signal. The modules532A-532D may additionally modulate the analog-converted signals onto aradio frequency (RF) carrier signal for transmission.

FIG. 5B shows a functional block diagram 500B for encoding data beforescrambling the data, as may be employed within the wireless device ofFIG. 2. The block diagram 500B may comprise the same components aspreviously described in connection with FIG. 5A with the exception thatthe scrambler 510A is not located upstream from the encoder parser 512A.Instead a scrambler 510B is located between the plurality of modules530A-530D and the plurality of modules 532A-532D. Thus, in functionalblock diagram 500B, data units are scrambled by scrambler 510B afterbeing encoded. In some implementations, the functional blocks of diagram500B may be configured to carry out some or all of the steps of any ofmethods that will be described in more detail in connection with FIGS.9, 11, 14, 16, 18 and 20 below.

FIG. 5C shows another functional block diagram 500C of exemplarycomponents that may be employed in the wireless device of FIG. 2. Thecomponents illustrated in functional block diagram 500C may correspondto one or more components as previously described in connection withFIG. 3 and/or FIG. 5B. For example, the encoder 550 may correspond toone or more components located in the signal flow from the encoderparser 512A to the modules 530A-530D, as previously described inconnection with FIG. 5B. The scrambler 510C may correspond to thescrambler 510B as previously described in connection with FIG. 5B. Thedigital-to-analog (D/A) converter 306 may be the same D/A converter 306as previously described in connection with FIG. 3 and/or may correspondto one or more circuits within the modules 532A-532D as previouslydescribed in connection with FIG. 5B. The transmit amplifier 308 withinthe transmitter 210 may be the same transmit amplifier 308 within thesame transmitter 210 as previously described in connection with FIG. 3.The components of FIG. 5C may allow for a data unit (e.g., the data unit500 b/500 c of FIGS. 5B/5C) to be encoded by encoder 550, then scrambledby scrambler 510C, prior to digital to analog conversion by D/A 306 andtransmission by transmitter 210. In an implementation, scrambler 510Cmay comprise a processor, such as processor 204 or DSP 220 of FIG. 2.Scrambler 510C may also include one or more of a processor, signalgenerator, transceiver, decoder, or a combination of hardware and/orsoftware component(s), circuits, and/or module(s). In an implementation,encoder 550 may comprise a processor, such as processor 204 or DSP 220of FIG. 2. Encoder 550 may also include one or more of a processor,signal generator, transceiver, decoder, or a combination of hardwareand/or software component(s), circuits, and/or module(s).

In some implementations, the components of functional block diagram 500Cadvantageously allow for the direct combining of primary data units andparity data units, or of primary data units and retransmissions of theprimary data units, at a receiving device in an attempt to recoverincorrectly decoded data. In some implementations, the components offunctional block diagram 500C overcome problems with directly combiningprimary data units and parity data units or retransmissions of theprimary data units arising from the data units being scrambled withdifferent sequences prior to encoding. In some implementations, thefunctional blocks of diagram 500C may be configured to carry out some orall of the steps of any of methods that will be described in more detailin connection with FIGS. 9, 11, 14, 16, 18 and 20 below.

FIG. 5D shows another functional block diagram 500D of exemplarycomponents that may be employed in the wireless device of FIG. 2. Atleast some of the components illustrated in functional block diagram500D may correspond to one or more components as previously described inconnection with FIGS. 4 and/or 5C. For example, the analog to digitalconverter 402 may be the same A/D converter 402 as previously describedin connection with FIG. 4. The receive amplifier 401 within receiver 212may be the same receive amplifier 401 within the receiver 212 aspreviously described in connection with FIG. 4. The descrambler 510D maycorrespond to and have the opposite operation from the scrambler 510C ofFIG. 5C (e.g., descramble a data unit that was previously scrambled byscrambler 510C). Likewise decoder 560 may correspond to and have theopposite operation from the encoder 550 of FIG. 5C (e.g., decode a dataunit that was previously encoded by encoder 550). The components of theblock diagram 500D may allow for a data unit, such as data unit 500b/500 c of FIGS. 5B/5C, to be descrambled by descrambler 510D, decodedby decoder 560, then combined with a parity data unit, or alternativelya retransmission of the data unit 500 b/500 c. In an implementation, thedescrambler 510D may comprise a processor, such as processor 204 or DSP220 of FIG. 2. The descrambler 510D may also include one or more of aprocessor, signal generator, transceiver, decoder, or a combination ofhardware and/or software component(s), circuits, and/or module(s). In animplementation, the decoder 560 may comprise a processor, such asprocessor 204 or DSP 220 of FIG. 2. The decoder 560 may also include oneor more of a processor, signal generator, transceiver, decoder, or acombination of hardware and/or software component(s), circuits, and/ormodule(s). In an implementation, combiner 570 may comprise a processor,such as processor 204 or DSP 220 of FIG. 2. Combiner 570 may alsoinclude one or more of a processor, signal generator, transceiver,decoder, or a combination of hardware and/or software component(s),circuits, and/or module(s).

In some implementations, the components of the functional block diagram500D advantageously allow for the direct combining of primary data unitsand parity data units or retransmissions of the primary data units at areceiving device in an attempt to recover incorrectly decoded data. Insome implementations, the components of the functional block diagram500D overcome problems with directly combining primary data units andparity data units or retransmissions of the primary data units arisingfrom the data units being scrambled with different sequences prior toencoding. In some implementations, the functional blocks of diagram 500Dmay be configured to carry out some or all of the steps of any ofmethods that will be described in more detail in connection with FIGS.10, 12, 13, 15, 17, 19 and 21 below.

FIG. 6A illustrates an example of a data unit or wireless frame 600 a.The data unit 600 a may comprise a PPDU for use with the wireless device202. The data unit 600 a includes a short training field (STF) and/or along training field (LTF) 610 a. Following STF/LTF 610 a in the dataunit 600 a is a SIGNAL field 620 a. The terms “SIGNAL unit,” “SIGNALfield,” “signal unit,” “signal field,” “SIG field,” and “sig field,” maybe used interchangeably herein. SIGNAL field 620 a may include variousinformation relating to the transmission rate, the length of the dataunit 600 a, and the like. SIGNAL field 620 a is contained in a preambleof data unit 600 a. The data unit 600 a may additionally comprise aSERVICE field 630 a. As is reflected in FIG. 6A, SERVICE field 630 a maycontain scrambler seed 650 a. Data/FCS 640 a may contain one or moredata fields and/or frame check sequence (FCS) fields. Data/FCS 640 a maybe scrambled based on scrambler seed 650 a. Importantly, when scramblerseed 650 a is contained in SERVICE field 630 a, bottlenecking may occurat a wireless device 202 that receives data unit 600 a if the code wordthat the SERVICE field 630 a is contained in is corrupted orincompletely received. In such a circumstance, additional parity on codewords after the first code word is not useful.

FIG. 6B illustrates an example of a data unit or wireless frame 600 b,in accordance with some implementations. The data unit 600 b maycomprise a PPDU for use with the wireless device 202. In someimplementations, data unit 600 b can be created by SIG field scramblerseed processor 230 of wireless device 202. The data unit 600 b includesSTF/LTF 610 b. Following STF/LTF 610 b in the data unit 600 b is aSIGNAL field 620 b. In an implementation, SIGNAL field 620 b may includevarious information relating to the transmission rate, the length of thedata unit 600 b, and the like. SIGNAL field 620 b is contained in apreamble of data unit 600 b.

In an implementation, SIGNAL field 620 b may contain scrambler seed 650b. Data/FCS 640 b may contain one or more data fields and/or frame checksequence (FCS) fields. Data/FCS 640 b (e.g., a portion of the data unit600 b) may be scrambled with a scrambler seed based on scrambler seed650 b. Data unit 600 b may optionally contain SERVICE field 630 b.Advantageously, the placement of scrambler seed 650 b in SIGNAL field620 b prevents the bottlenecking discussed in relation to data unit 600a. Bottlenecking is prevented because SIGNAL field 620 b, as part of thepreamble of data unit 600 b, is transferred at more robust modulationlevels (e.g., at a lower data rate) than SERVICE field 630 b. Further,if the preamble of data unit 600 b fails, the entire packet must beretransmitted anyway, thus not allowing a bottleneck to occur.Additionally, in one implementation, by containing scrambler seed 650 bin SIGNAL field 620 b, data unit 600 b may optionally not containSERVICE field 630 b. In another implementation, SERVICE field 630 b mayalso optionally be retained, but simply not used, in order to retain thecurrent design of data unit 600 b. In another implementation, SERVICEfield 630 b may optionally have all of its bits set to 0. In anotherimplementation, scrambler seed 650 b may be less than 7 bits. Forexample, in this implementation scrambler seed 650 b may be 1 or 2 bits.

In an implementation, the placement of scrambler seed 650 b in SIGNALfield 620 b is also advantageous as it allows for more efficient use ofa parity data unit that also contains a scrambler seed in its SIGNALfield. In this implementation, a wireless device 202 that receives dataunit 600 b and a parity data unit will know the scrambler seed of eachand can compensate for the difference of the scrambler seeds. In animplementation, compensation comprises changing the signs of the storeddata values at the receiver based on the difference of the data unit 600b scrambler seed and the parity data unit scrambler seed. After wirelessdevice 202 compensates for the difference of the scrambler seeds,wireless device 202 can then combine the parities directly.

In an implementation, SIGNAL field 620 b does not contain scrambler seed650 b. Instead, scrambler seed 650 b is determined from one or moreparameters indicated in SIGNAL field 620 b, thus rendering insertion ofscrambler seed 650 b into SIGNAL field 620 b unnecessary.Advantageously, determining scrambler seed 650 b from one or moreparameters indicated in SIGNAL field 620 b prevents the bottleneckingdiscussed in relation to data unit 600 a. Bottlenecking is preventedbecause SIGNAL field 620 b, as part of the preamble of data unit 600 b,is transferred at more robust modulation levels (e.g., at a lower datarate) than SERVICE field 630 b. Further, if the preamble of data unit600 b fails, the entire packet must be retransmitted anyway, thus notallowing a bottleneck to occur. Additionally, in one implementation, bydetermining scrambler seed 650 b from one or more parameters in SIGNALfield 620 b, data unit 600 b may optionally not contain SERVICE field630 b. In another implementation, SERVICE field 630 b may alsooptionally be retained, but simply not used, in order to retain thecurrent design of data unit 600 b. In another implementation, SERVICEfield 630 b may optionally have all of its bits set to 0. In anotherimplementation, SERVICE field 630 b may optionally contain less than 7bits.

FIG. 6C illustrates an example of a data unit or wireless frame 600 c,in accordance with some implementations. The data unit 600 c maycomprise a PPDU for use with the wireless device 202. In someimplementations, data unit 600 c can be created by DSP 220 of wirelessdevice 202. The data unit 600 s includes STF/LTF 610 c. FollowingSTF/LTF 610 c in the data unit 600 c is a SIGNAL field 620 c. In animplementation, SIGNAL field 620 c may include various informationrelating to the transmission rate, the length of the data unit 600 c,and the like. SIGNAL field 620 c is contained in a preamble of data unit600 c. In an implementation, as is reflected in FIG. 6C, a plurality ofscrambler seeds may be contained in data unit 600 c, with each scramblerseed (650 c 1, 650 c 2, 650 cN) being associated with a particular codeword/data field (640 c 1, 640 c 2, 640 cN). In this implementation, eachscrambler seed (650 c 1, 650 c 2, 650 cN) is contained before the codeword/data field (640 c 1, 640 c 2, 640 cN) it is associated with. Inthis implementation, the scrambling/encoding procedure used at wirelessdevice 202 must be adapted so that data portion sizes are predefined inorder to allow scrambling before each code word. In someimplementations, the predefined sizes may be noted in SIGNAL field 620c. Advantageously, this implementation prevents the bottleneckingdiscussed in relation to data unit 600 a as each code word/data field(e.g., a portion of the data unit 600 c) is scrambled independently ofother code words/data fields. As one skilled in the art will recognize,both greater and fewer numbers of sets of scrambler seeds and associatedcode words/data fields are possible than are reflected in FIG. 6C.

The data units 600 b and 600 c illustrated in FIGS. 6B and 6C are onlyexamples of data units that may be used in the system 100 and/or withthe wireless device 202. Those having ordinary skill in the art willappreciate that one or more symbols or fields may be included in thedata units 600 b and 600 c that are not illustrated in FIGS. 6B and 6C,and one or more of the illustrated fields or symbols may be omitted.

Some implementations of wireless networks may utilize different versionsof a wireless frame 600 to reduce overhead or the power required toreceive the wireless frame. For example, some implementations mayutilize a wireless frame that is physically shorter, or includes fewerbytes, than frames 600 b and/or 600 c.

FIG. 7A shows an exemplary structure of a media access control protocoldata unit (MPDU) frame 700 a. As shown, the MPDU frame 700 includes 11different fields: a frame control (fc) field 710, aduration/identification (dur) field 725, a receiver address (a1) field730, a transmitter address (a2) field 735, a destination address (a3)field 740, a sequence control (sc) field 745, a fourth address (a4)field 750, a quality of service (QoS) control (qc) field 755, a HighThroughput (HT) control field 760, the frame body 765, and a frame checksequence (FCS) field 770. The fields 710-760 make up the MAC header 702.

Each of the fields of a media access control frame may be considered amedia access control parameter. Additionally, each field may becomprised of one or more sub-fields or fields. For example, framecontrol field 710 of media access control header 702 may be comprised ofmultiple subfields, such as a protocol version, type field, subtypefield, and other fields. Each of these subfields or fields may also beconsidered a media access control parameter. In some implementations,individual bits of a media access control frame may be considered amedia access control parameter.

Each of the a1, a2, a3, and a4 fields 730, 735, 740, and 750 comprises afull MAC address of a device, which is a 48-bit (6 octet) value. FIG. 7Afurther indicates the size in octets of each of the fields 710-770. Theframe body field 765 comprises a variable number of octets (e.g., from 0to 7951). Summing the value of all of the field sizes gives the overallsize of the MAC header 702, which is 38 octets. The total size of agiven MPDU may be on the order of 200 octets.

MPDU frames of different types may include only a portion of the fieldsshown in FIG. 7A. For example, if a MPDU frame is a control frame, theMAC header of the MPDU frame may not include the QoS control field 760or the HT control field 760. In addition, depending on the type, theMPDU frame 700 may include additional fields. However, in some cases,regardless of the type, the MPDU frame 700 may include the frame controlfield 710.

FIG. 7B shows an exemplary implementation of a media access controlprotocol data unit (MPDU) frame 700 b containing a scrambler seed 780.In this implementation, scrambler seed 780 is prepended to MAC header702, thus advantageously allowing for a different scrambler seed foreach MPDU.

FIG. 8A shows an exemplary structure of an aggregated MPDU (A-MPDU)frame 800 a. As shown, the A-MPDU frame 800 a includes a variable number(n) of A-MPDU sub-frames, as shown 805 a, 805 b, and 805 n. Each of theA-MPDU sub-frames 805 a, 805 b, and 805 n may in some aspects becomprised of an MPDU delimiter field 810 a, an MPDU frame 700 a, and oneor more pad bytes. The MPDU frame 700 a may in some aspects conformsubstantially with the MPDU frame 700 a illustrated in FIG. 7A. Each ofthe MPDU delimiter fields, for example, MPDU delimiter field 810 a, mayinclude an end of frame (EOF) field 812 a, a reserved field 814 a, anMPDU length field 817 a, a CRC field 818 a, and a delimiter signaturefield 820 a.

FIG. 8B shows an exemplary implementation of an MPDU delimiter field 800b including a scrambler seed 850 b. In some implementations, MPDUdelimiter field 800 b can be created by DSP 220 of wireless device 202.As shown, scrambler seed 850 b is included in the reserved bits 814 b ofMPDU delimiter field 800 b. Advantageously, this implementation allowsfor different scrambler seeds for each MPDU, thus preventing thebottlenecking discussed in relation to data unit 500 a.

FIG. 8C shows another exemplary implementation of an MPDU delimiterfield 800 c including a scrambler seed 850 c. In some implementations,MPDU delimiter field 800 c can be created by DSP 220 of wireless device202. As shown, scrambler seed 850 c is included in the delimitersignature 820 c of MPDU delimiter field 800 c. Advantageously, thisimplementation allows for different scrambler seeds for each MPDU, thuspreventing the bottlenecking discussed in relation to data unit 500 a.

FIG. 9 shows a flow chart of an exemplary method 900 that may beemployed within the wireless device of FIG. 2. The method 900 can beimplemented in whole or in part by the devices described herein, such asthe wireless device 202 shown in FIG. 2. FIG. 9 may be performed ateither AP 104 or STAs 106. Although the illustrated method 900 isdescribed herein with reference to the wireless communication system 100discussed above with respect to FIG. 1, and the wireless device 202discussed in FIG. 2, a person having ordinary skill in the art willappreciate that the illustrated method 900 can be implemented by anotherdevice described herein, or any other suitable device. Although theillustrated method 900 is described herein with reference to aparticular order, in various implementations, blocks herein may beperformed in a different order, or omitted, and additional blocks may beadded.

At block 902, a scrambling sequence is determined. At block 904, ascrambler seed indicating the scrambling sequence is inserted into asignal field of a first data unit configured to be wirelesslytransmitted. For example, with reference to FIG. 6B, scrambler seed 650b is inserted into signal field 620 b of data unit 600 b. A processorsuch as SIG field scrambler seed processor 230 of FIG. 2 could performsuch an insertion, although a person of ordinary skill in the art willappreciate that block 904 can be implemented by another device describedherein, or any other suitable device.

At block 906, at least part of the data unit is scrambled based at leastin part on the scrambler seed. For example, again with reference to FIG.6B, data unit 600 b is scrambled based at least in part on scramblerseed 650 b. A processor such as SIG field scrambler seed processor 230of FIG. 2 could perform such scrambling, although a person of ordinaryskill in the art will appreciate that block 906 can be implemented byanother device described herein, or any other suitable device.

FIG. 10 shows a flow chart of another exemplary method 1000 that may beemployed within the wireless device of FIG. 2. The method 1000 can beimplemented in whole or in part by the devices described herein, such asthe wireless device 202 shown in FIG. 2. FIG. 10 may be performed ateither AP 104 or STAs 106. Although the illustrated method 1000 isdescribed herein with reference to the wireless communication system 100discussed above with respect to FIG. 1, and the wireless device 202discussed in FIG. 2, a person having ordinary skill in the art willappreciate that the illustrated method 1000 can be implemented byanother device described herein, or any other suitable device. Althoughthe illustrated method 1000 is described herein with reference to aparticular order, in various implementations, blocks herein may beperformed in a different order, or omitted, and additional blocks may beadded.

At block 1002, an at least partly scrambled first data unit is received.A receiver such as receiver 212 of FIG. 2 could perform such a function,although a person of ordinary skill in the art will appreciate thatblock 1002 can be implemented by another device described herein, or anyother suitable device.

At block 1004, a scrambler seed is identified in a signal field of theat least partly scrambled first data unit. For example, with referenceto FIG. 6B, scrambler seed 650 b is identified in signal field 620 b ofdata unit 600 b. A processor such as SIG field scrambler seed processor230 of FIG. 2 could perform such an identification, although a person ofordinary skill in the art will appreciate that block 1004 can beimplemented by another device described herein, or any other suitabledevice.

At block 1006, at least a portion of the at least partly scrambled firstdata unit is descrambled based at least in part on the identifiedscrambler seed. For example, with reference to FIG. 6B, at least part ofdata unit 600 b is descrambled based at least in part on scrambler seed650 b. A processor such as SIG field scrambler seed processor 230 ofFIG. 2 could perform such descrambling, although a person of ordinaryskill in the art will appreciate that block 1006 can be implemented byanother device described herein, or any other suitable device.

FIG. 11 shows a flow chart of yet another exemplary method 1100 that maybe employed within the wireless device of FIG. 2. The method 1100 can beimplemented in whole or in part by the devices described herein, such asthe wireless device 202 shown in FIG. 2. FIG. 11 may be performed ateither AP 114 or STAs 116. Although the illustrated method 1100 isdescribed herein with reference to the wireless communication system 110discussed above with respect to FIG. 1, and the wireless device 202discussed in FIG. 2, a person having ordinary skill in the art willappreciate that the illustrated method 1100 can be implemented byanother device described herein, or any other suitable device. Althoughthe illustrated method 1100 is described herein with reference to aparticular order, in various implementations, blocks herein may beperformed in a different order, or omitted, and additional blocks may beadded.

At block 1102, a scrambler seed is determined. A processor such as DSP220 of FIG. 2 could perform such a determination, although a person ofordinary skill in the art will appreciate that block 1102 can beimplemented by another device described herein, or any other suitabledevice.

At block 1104, one or more parameters indicative of the scramblingsequence are inserted into a signal field of a first data unitconfigured to be wirelessly transmitted. For example, with reference toFIG. 6B, the one or more parameters may be utilized to indicate thescrambler seed 650 b in signal field 620 b of data unit 600 b. Aprocessor such as DSP 220 of FIG. 2 could perform such an insertion,although a person of ordinary skill in the art will appreciate thatblock 1104 can be implemented by another device described herein, or anyother suitable device.

At block 1106 at least a portion of the first data unit is scrambledbased at least in part on the scrambler seed determined in block 1102and as indicated by the one or more parameters inserted in block 1104.For example, again with reference to FIG. 6B, data unit 600 b isscrambled based at least in part on scrambler seed 650 b. A processorsuch as DSP 220 of FIG. 2 could perform such scrambling, although aperson of ordinary skill in the art will appreciate that block 1106 canbe implemented by another device described herein, or any other suitabledevice.

At block 1108 the scrambled first data unit is transmitted, wherein thesignal field of the data unit is transmitted via a different modulationscheme than is a service field of the first data unit (e.g., the signalfield is transmitted at a lower data rate than the service field, orrecited in reciprocal, the service field is transmitted at a higher datarate than the signal field). A transmitter such as transmitter 210 ofFIG. 2 could perform such a function, although a person of ordinaryskill in the art will appreciate that block 1320 can be implemented byanother device described herein, or any other suitable device.

FIG. 12 shows a flow chart of yet another exemplary method 1200 that maybe employed within the wireless device of FIG. 2. The method 1200 can beimplemented in whole or in part by the devices described herein, such asthe wireless device 202 shown in FIG. 2. FIG. 12 may be performed ateither AP 104 or STAs 106. Although the illustrated method 1200 isdescribed herein with reference to the wireless communication system 100discussed above with respect to FIG. 1, and the wireless device 202discussed in FIG. 2, a person having ordinary skill in the art willappreciate that the illustrated method 1200 can be implemented byanother device described herein, or any other suitable device. Althoughthe illustrated method 1200 is described herein with reference to aparticular order, in various implementations, blocks herein may beperformed in a different order, or omitted, and additional blocks may beadded.

At block 1202, an at least partly scrambled first data unit is received.A receiver such as receiver 212 of FIG. 2 could perform such a function,although a person of ordinary skill in the art will appreciate thatblock 1202 can be implemented by another device described herein, or anyother suitable device.

At block 1204, a descrambler seed is determined based at least in parton one or more parameters indicated in a signal field of the at leastpartly scrambled first data unit. For example, with reference to FIG.6B, scrambler seed 650 b is determined based on one or more parametersindicated in signal field 620 b of data unit 600 b. A processor such asDSP 220 of FIG. 2 could perform such a determination, although a personof ordinary skill in the art will appreciate that block 1204 can beimplemented by another device described herein, or any other suitabledevice.

At block 1206, at least a portion of the at least partly scrambled firstdata unit is descrambled based at least in part on the determineddescrambler seed. For example, with reference to FIG. 6B, at least partof data unit 600 b is descrambled based at least in part on scramblerseed 650 b. A processor such as DSP 220 of FIG. 2 could perform suchdescrambling, although a person of ordinary skill in the art willappreciate that block 1206 can be implemented by another devicedescribed herein, or any other suitable device.

FIG. 13 shows a flow chart of yet another exemplary method 1300 that maybe employed within the wireless device of FIG. 2. The method 1300 can beimplemented in whole or in part by the devices described herein, such asthe wireless device 202 shown in FIG. 2. FIG. 13 may be performed ateither AP 104 or STAs 106. Although the illustrated method 1300 isdescribed herein with reference to the wireless communication system 100discussed above with respect to FIG. 1, and the wireless device 202discussed in FIG. 2, a person having ordinary skill in the art willappreciate that the illustrated method 1300 can be implemented byanother device described herein, or any other suitable device. Althoughthe illustrated method 1300 is described herein with reference to aparticular order, in various implementations, blocks herein may beperformed in a different order, or omitted, and additional blocks may beadded.

First, at block 1302, an at least partly scrambled first data unit isreceived. A receiver such as receiver 212 of FIG. 2 could perform such afunction, although a person of ordinary skill in the art will appreciatethat block 1302 can be implemented by another device described herein,or any other suitable device.

Next, at block 1304, a scrambler seed is identified in a signal field ofthe at least partly scrambled first data unit. For example, withreference to FIG. 6B, scrambler seed 650 b is identified in signal field620 b of data unit 600 b. A processor such as SIG field scrambler seedprocessor 230 of FIG. 2 could perform such an identification, although aperson of ordinary skill in the art will appreciate that block 1304 canbe implemented by another device described herein, or any other suitabledevice.

Next, at block 1306, at least a portion of the at least partly scrambledfirst data unit is descrambled based at least in part on the identifiedscrambler seed. For example, with reference to FIG. 6B, at least aportion of data unit 600 b is descrambled based at least in part onscrambler seed 650 b. A processor such as SIG field scrambler seedprocessor 230 of FIG. 2 could perform such descrambling, although aperson of ordinary skill in the art will appreciate that block 1306 canbe implemented by another device described herein, or any other suitabledevice.

At block 1308, a parity data unit is received that is scrambled based atleast in part on a scrambler seed included in the signal field of theparity data unit. A receiver such as receiver 212 of FIG. 2 couldperform such a function, although a person of ordinary skill in the artwill appreciate that block 1308 can be implemented by another devicedescribed herein, or any other suitable device.

At block 1310, a scrambler seed is identified in a signal field of theparity data unit. For example, with reference to FIG. 6B, scrambler seed650 b is identified in signal field 620 b of data unit 600 b. Aprocessor such as SIG field scrambler seed processor 230 of FIG. 2 couldperform such an identification, although a person of ordinary skill inthe art will appreciate that block 1310 can be implemented by anotherdevice described herein, or any other suitable device.

At block 1312, compensation occurs for the difference of the first dataunit scrambler seed and the parity data unit scrambler seed. In animplementation, compensation comprises changing the signs of the storeddata values at the receiver based on the difference of the first dataunit scrambler seed and the parity data unit scrambler seed. A processorsuch as SIG field scrambler seed processor 230 of FIG. 2 could performsuch a compensation, although a person of ordinary skill in the art willappreciate that block 1312 can be implemented by another devicedescribed herein, or any other suitable device.

At block 1314, the first data unit and the parity data unit arecombined. The result of block 1314 should indicate whether theinformation in the first data unit was transmitted accurately. Aprocessor such as SIG field scrambler seed processor 230 of FIG. 2 couldperform such combining, although a person of ordinary skill in the artwill appreciate that block 1314 can be implemented by another devicedescribed herein, or any other suitable device.

FIG. 14 shows a flow chart of yet another exemplary method 1400 that maybe employed within the wireless device of FIG. 2. The method 1400 can beimplemented in whole or in part by the devices described herein, such asthe wireless device 202 shown in FIG. 2. FIG. 14 may be performed ateither AP 104 or STAs 106. Although the illustrated method 1400 isdescribed herein with reference to the wireless communication system 100discussed above with respect to FIG. 1, and the wireless device 202discussed in FIG. 2, a person having ordinary skill in the art willappreciate that the illustrated method 1400 can be implemented byanother device described herein, or any other suitable device. Althoughthe illustrated method 1400 is described herein with reference to aparticular order, in various implementations, blocks herein may beperformed in a different order, or omitted, and additional blocks may beadded. In some implementations, method 1400 is advantageous as it allowsfor the direct combining of first data units and parity data units in anattempt to recover wrongly decoded data. In some implementations, method1400 overcomes problems with directly combining first data units andparity data units arising due to the data units being scrambled withdifferent sequences prior to encoding.

First, at block 1402, a first data unit is encoded. A processor such asDSP 220 of FIG. 2 could perform such encoding, as could encoder 520C ofFIG. 5C, although a person of ordinary skill in the art will appreciatethat block 1402 can be implemented by another device described herein,or any other suitable device.

Next, at block 1404, the encoded first data unit is scrambled. Block1404 must occur after block 1402. A processor such as DSP 220 of FIG. 2could perform such scrambling, as could scrambler 510C of FIG. 5C,although a person of ordinary skill in the art will appreciate thatblock 1404 can be implemented by another device described herein, or anyother suitable device.

Next, at block 1406, the scrambled encoded first data unit istransmitted wirelessly. A transmitter such as transmitter 210 of FIGS. 2and 5C could perform such a function, although a person of ordinaryskill in the art will appreciate that block 1406 can be implemented byanother device described herein, or any other suitable device.

Next, at block 1408, a parity data unit is encoded. A processor such asDSP 220 of FIG. 2 could perform such encoding, as could encoder 520C ofFIG. 5C, although a person of ordinary skill in the art will appreciatethat block 1408 can be implemented by another device described herein,or any other suitable device.

Next, at block 1410, the encoded parity data unit is scrambled. Block1410 must occur after block 1408. A processor such as DSP 220 of FIG. 2could perform such scrambling, as could scrambler 510C of FIG. 5C,although a person of ordinary skill in the art will appreciate thatblock 1410 can be implemented by another device described herein, or anyother suitable device.

Next, at block 1412, the scrambled encoded parity data unit istransmitted wirelessly. A transmitter such as transmitter 210 of FIGS. 2and 5C could perform such a function, although a person of ordinaryskill in the art will appreciate that block 1406 can be implemented byanother device described herein, or any other suitable device.

FIG. 15 shows a flow chart of yet another exemplary method 1500 that maybe employed within the wireless device of FIG. 2. The method 1500 can beimplemented in whole or in part by the devices described herein, such asthe wireless device 202 shown in FIG. 2. FIG. 15 may be performed ateither AP 104 or STAs 106. Although the illustrated method 1500 isdescribed herein with reference to the wireless communication system 100discussed above with respect to FIG. 1, and the wireless device 202discussed in FIG. 2, a person having ordinary skill in the art willappreciate that the illustrated method 1500 can be implemented byanother device described herein, or any other suitable device. Althoughthe illustrated method 1500 is described herein with reference to aparticular order, in various implementations, blocks herein may beperformed in a different order, or omitted, and additional blocks may beadded. In some implementations, method 1500 is advantageous as it allowsfor the direct combining of primary data units and parity data units inan attempt to recover wrongly decoded data. In some implementations,method 1500 overcomes problems with directly combining primary dataunits and parity data units arising due to the data units beingscrambled with different sequences prior to encoding.

First, at block 1502, a scrambled encoded primary data unit is received.A receiver such as receiver 212 of FIGS. 2 and 5D could perform such afunction, although a person of ordinary skill in the art will appreciatethat block 1502 can be implemented by another device described herein,or any other suitable device.

Next, at block 1504, the scrambled encoded primary data unit isdescrambled. A processor such as DSP 220 of FIG. 2 could perform suchdescrambling, as could descrambler 510D of FIG. 5D, although a person ofordinary skill in the art will appreciate that block 1504 can beimplemented by another device described herein, or any other suitabledevice.

Next, at block 1506, the descrambled encoded primary data unit isdecoded. A processor such as DSP 220 of FIG. 2 could perform suchdecoding, as could decoder 520D of FIG. 5D, although a person ofordinary skill in the art will appreciate that block 1506 can beimplemented by another device described herein, or any other suitabledevice.

Next, at block 1508, a scrambled encoded parity data unit is received. Areceiver such as receiver 212 of FIGS. 2 and 5D could perform such afunction, although a person of ordinary skill in the art will appreciatethat block 1508 can be implemented by another device described herein,or any other suitable device.

Next, at block 1510, the scrambled encoded parity data unit isdescrambled. A processor such as DSP 220 of FIG. 2 could perform suchdescrambling, as could descrambler 510D of FIG. 5D, although a person ofordinary skill in the art will appreciate that block 1510 can beimplemented by another device described herein, or any other suitabledevice.

Next, at block 1512, the descrambled encoded parity data unit isdecoded. A processor such as DSP 220 of FIG. 2 could perform suchdecoding, as could decoder 520D of FIG. 5D, although a person ofordinary skill in the art will appreciate that block 1512 can beimplemented by another device described herein, or any other suitabledevice.

Next, at block 1514, the descrambled decoded primary data unit iscombined with the descrambled decoded parity data unit. A processor suchas DSP 220 of FIG. 2 could perform such combining, as could combiner530D of FIG. 5D, although a person of ordinary skill in the art willappreciate that block 1514 can be implemented by another devicedescribed herein, or any other suitable device.

FIG. 16 shows a flow chart of yet another exemplary method 1600 that maybe employed within the wireless device of FIG. 2. The method 1600 can beimplemented in whole or in part by the devices described herein, such asthe wireless device 202 shown in FIG. 2. FIG. 16 may be performed ateither AP 104 or STAs 106. Although the illustrated method 1600 isdescribed herein with reference to the wireless communication system 100discussed above with respect to FIG. 1, and the wireless device 202discussed in FIG. 2, a person having ordinary skill in the art willappreciate that the illustrated method 1600 can be implemented byanother device described herein, or any other suitable device. Althoughthe illustrated method 1600 is described herein with reference to aparticular order, in various implementations, blocks herein may beperformed in a different order, or omitted, and additional blocks may beadded.

At block 1602, a scrambling sequence may be determined. In someimplementations, the scrambling sequence is fixed, for example accordingto a technical standard or access point. In some implementations, thescrambling sequence is random. In yet other implementations, as will bedescribed in more detail in connection with FIGS. 18 and 19, thescrambling sequence may be determined based at least in part on a timingrelative to when the first data unit is transmitted. For example, insome implementations, the AP 104 or STAs 106 may determine whatscrambling sequence to utilize based on a timing of transmission of thefirst data unit relative to a start or end of a beacon interval (i.e.,the interval between successive beacon transmissions).

At block 1604, an indication of the scrambling sequence is inserted intoa signal field of a first data unit configured to be transmittedwirelessly. For example in some implementations, with reference to FIG.6B, a scrambler seed 650 b indicating the scrambling sequence isinserted into the signal field 620 b of data unit 600 b. In some otherimplementations, the indication may comprise one or more parametersindicating the scrambling sequence. A processor such as DSP 220 of FIG.2 could perform the insertion carried out at block 1602, although aperson of ordinary skill in the art will appreciate that block 1602 canbe implemented by another device described herein, or any other suitabledevice.

At block 1606, at least a portion of the first data unit is scrambledbased at least on the indication inserted into the signal field of thefirst data unit. In one implementation, with reference to FIG. 6B, atleast a portion of the data unit 600 b is scrambled based at least onscrambler seed 650 b. A processor such as DSP 220 of FIG. 2 couldperform the scrambling carried out at block 1606, although a person ofordinary skill in the art will appreciate that block 1606 can beimplemented by another device described herein, or any other suitabledevice.

At block 1608, at least a portion of a second data unit is scrambled,the second data unit being configured to be transmitted wirelessly. Insome implementations, the second data unit is scrambled based at leastthe indication of the scrambling sequence inserted into the first dataunit. In some other implementations, the second data unit is scrambledbased at least on an indication of a scrambling sequence inserted intothe second data unit. In some implementations, the second data unitcomprises a retransmission of the first data unit. In someimplementations the second data unit comprises a parity data unit, theparity data unit being associated with the first data unit. A processorsuch as DSP 220 of FIG. 2 could perform the scrambling carried out atblock 1608, although a person of ordinary skill in the art willappreciate that block 1608 can be implemented by another devicedescribed herein, or any other suitable device.

FIG. 17 shows a flow chart of yet another exemplary method 1700 that maybe employed within the wireless device of FIG. 2. The method 1700 can beimplemented in whole or in part by the devices described herein, such asthe wireless device 202 shown in FIG. 2. Exemplary method 1700 may beperformed at either AP 104 or STAs 106. Although the illustrated method1700 is described herein with reference to the wireless communicationsystem 100 discussed above with respect to FIG. 1, and the wirelessdevice 202 discussed in FIG. 2, a person having ordinary skill in theart will appreciate that the illustrated method 1700 can be implementedby another device described herein, or any other suitable device.Although the illustrated method 1700 is described herein with referenceto a particular order, in various implementations, blocks herein may beperformed in a different order, or omitted, and additional blocks may beadded.

At block 1702, an at least partly scrambled first data unit is receivedwirelessly. A receiver such as receiver 212 of FIG. 2 could perform sucha function, although a person of ordinary skill in the art willappreciate that block 1702 can be implemented by another devicedescribed herein, or any other suitable device. In one implementation,with reference to FIG. 6B, data unit 600 b is a first data unit.

At block 1704, at least a portion of the at least partly scrambled firstdata unit is descrambled based at least on an indication of a scramblingsequence located in a signal field of the first data unit. In oneimplementation, with reference to FIG. 6B, data unit 600 b isdescrambled based on scrambler seed 650 b. In some otherimplementations, the data unit may be descrambled based on one or moreparameters indicating the scrambling sequence inserted the signal field.A processor such as DSP 220 of FIG. 2 could perform the descramblingcarried out at block 1704, although a person of ordinary skill in theart will appreciate that block 1704 can be implemented by another devicedescribed herein, or any other suitable device.

At block 1706, an at least partly scrambled second data unit is receivedwirelessly. A receiver such as receiver 212 of FIG. 2 could perform sucha function, although a person of ordinary skill in the art willappreciate that block 1706 can be implemented by another devicedescribed herein, or any other suitable device. In some implementations,the second data unit comprises a retransmission of the first data unit.In some implementations the second data unit comprises a paritytransmission, the parity transmission being associated with the firstdata unit.

At block 1708, at least a portion of the at least partly scrambledsecond data unit is descrambled. In some implementations, thedescrambling may be based at least on the scrambler seed or indicationof the scrambling sequence located in the signal field of the first dataunit. In some other implementations, the descrambling may be based atleast on a scrambler seed or indication of the scrambling sequenceinserted in a signal field of the second data unit. A processor such asDSP 220 of FIG. 2 could perform the descrambling carried out at block1708, although a person of ordinary skill in the art will appreciatethat block 1708 can be implemented by another device described herein,or any other suitable device.

FIG. 18 shows a flow chart of yet another exemplary method 1800 that maybe employed within the wireless device of FIG. 2. The method 1800 can beimplemented in whole or in part by the devices described herein, such asthe wireless device 202 shown in FIG. 2. FIG. 18 may be performed ateither AP 104 or STAs 106. Although the illustrated method 1800 isdescribed herein with reference to the wireless communication system 100discussed above with respect to FIG. 1, and the wireless device 202discussed in FIG. 2, a person having ordinary skill in the art willappreciate that the illustrated method 1800 can be implemented byanother device described herein, or any other suitable device. Althoughthe illustrated method 1800 is described herein with reference to aparticular order, in various implementations, blocks herein may beperformed in a different order, or omitted, and additional blocks may beadded.

At block 1802, a plurality of scrambler seeds are inserted into a dataunit comprising a plurality of data portions, each scrambler seedassociated with a respective data portion. In one implementation, withreference to FIG. 6C, scrambler seeds (650 c 1, 650 c 2, 650 cN) areinserted into data unit 600 c before the code word/data field (640 c 1,640 c 2, 640 cN) they are each respectively associated with. In thisimplementation, a data portion is comprised of each code word/data field(640 c 1, 640 c 2, 640 cN). In another implementation, with reference toFIG. 8A, each particular MPDU frame 700 a of A-MPDU 800 a can have anassociated scrambler seed inserted, such as is reflected in FIG. 7B withMPDU 700 b having its MAC Header 702 prepended by scrambler seed 780. Inthis implementation, a data portion is comprised of each MPDU frame 700a. In another implementation, with reference to FIG. 8A, each A-MPDUsubframe (805 a, 805 b, 805 n) can have an associated scrambler seedinserted, such as is reflected in FIG. 8B with MPDU delimiter field 800b having scrambler seed 850 b inserted into reserved bits 814 b, and asis reflected in FIG. 8C with MPDU delimiter field 800 c having scramblerseed 850 c inserted into delimiter signature 820 c. In thisimplementation, a data portion is comprised of each MPDU frame 700 a. Aprocessor such as DSP 220 of FIG. 2 could perform the insertion carriedout at block 1802, although a person of ordinary skill in the art willappreciate that block 1802 can be implemented by another devicedescribed herein, or any other suitable device.

At block 1804, each data portion is scrambled based at least in part onan associated scrambler seed. In one implementation, with reference toFIG. 6C, code words/data fields (640 c 1, 640 c 2, 640 cN) are scrambledat least in part based on their respectively associated scrambler seeds(650 c 1, 650 c 2, 650 cN). In another implementation, with reference toFIG. 7B, each MPDU frame 700 b is scrambled based on a scrambler seed780. In another implementation, with reference to FIGS. 8A and 8B, eachMPDU frame 700 a is scrambled based on its associated scrambler seed 850b. In another implementation, with reference to FIGS. 8A and 8C, eachMPDU frame 700 a is scrambled based on its associated scrambler seed 850c. A processor such as DSP 220 of FIG. 2 could perform the scramblingcarried out at block 1804, although a person of ordinary skill in theart will appreciate that block 1804 can be implemented by another devicedescribed herein, or any other suitable device.

At block 1806, the data unit is transmitted. A transmitter such astransmitter 210 of FIG. 2 could perform such a function, although aperson of ordinary skill in the art will appreciate that block 1806 canbe implemented by another device described herein, or any other suitabledevice.

FIG. 19 shows a flow chart of yet another exemplary method 1900 that maybe employed within the wireless device of FIG. 2. The method 1900 can beimplemented in whole or in part by the devices described herein, such asthe wireless device 202 shown in FIG. 2. FIG. 19 may be performed ateither AP 104 or STAs 106. Although the illustrated method 1900 isdescribed herein with reference to the wireless communication system 100discussed above with respect to FIG. 1, and the wireless device 202discussed in FIG. 2, a person having ordinary skill in the art willappreciate that the illustrated method 1900 can be implemented byanother device described herein, or any other suitable device. Althoughthe illustrated method 1900 is described herein with reference to aparticular order, in various implementations, blocks herein may beperformed in a different order, or omitted, and additional blocks may beadded.

At block 1902, a data unit comprising a plurality of data portions isreceived. In one implementation, with reference to FIG. 6C, data unit600 c is comprised of a plurality of data portions in the form of codewords/data fields (640 c 1, 640 c 2, 640 cN). In another implementation,with reference to FIG. 8A, A-MPDU frame 800 a is comprised of aplurality of data portions in the form of MPDU frames 700 a. A receiversuch as receiver 212 of FIG. 2 could perform such a function, although aperson of ordinary skill in the art will appreciate that block 1902 canbe implemented by another device described herein, or any other suitabledevice.

At block 1904, a plurality of scrambler seeds are identified in the dataunit. In one implementation, with reference to FIG. 6C, scrambler seeds(650 c 1, 650 c 2, 650 cN) are identified. In another implementation,with reference to FIG. 7B, scrambler seed 780 is identified for eachMPDU 700 b. In another implementation, with reference to FIG. 8B,scrambler seed 850 b is identified for each MPDU. In anotherimplementation, with reference to FIG. 8C, scrambler seed 850 c isidentified for each MPDU. A processor such as DSP 220 of FIG. 2 couldperform the identification carried out at block 1904, although a personof ordinary skill in the art will appreciate that block 1904 can beimplemented by another device described herein, or any other suitabledevice.

At block 1906, each data portion is descrambled based at least in parton an associated scrambler seed. In one implementation, with referenceto FIG. 6C, code words/data fields (640 c 1, 640 c 2, 640 cN) aredescrambled at least in part based on their respectively associatedscrambler seeds (650 c 1, 650 c 2, 650 cN). In another implementation,with reference to FIG. 7B, each MPDU frame 700 b is descrambled based ona scrambler seed 780. In another implementation, with reference to FIGS.8A and 8B, each MPDU frame 700 a is descrambled based on its associatedscrambler seed 850 b. In another implementation, with reference to FIGS.8A and 8C, each MPDU frame 700 a is descrambled based on its associatedscrambler seed 850 c. A processor such as DSP 220 of FIG. 2 couldperform the descrambling carried out at block 1906, although a person ofordinary skill in the art will appreciate that block 1906 can beimplemented by another device described herein, or any other suitabledevice.

FIG. 20 shows a flow chart of yet another exemplary method 2000 that maybe employed within the wireless device of FIG. 2. The method 2000 can beimplemented in whole or in part by the devices described herein, such asthe wireless device 202 shown in FIG. 2. FIG. 20 may be performed ateither AP 104 or STAs 106. Although the illustrated method 2000 isdescribed herein with reference to the wireless communication system 100discussed above with respect to FIG. 1, and the wireless device 202discussed in FIG. 2, a person having ordinary skill in the art willappreciate that the illustrated method 2000 can be implemented byanother device described herein, or any other suitable device. Althoughthe illustrated method 2000 is described herein with reference to aparticular order, in various implementations, blocks herein may beperformed in a different order, or omitted, and additional blocks may beadded.

First, at block 2002, a scrambler seed is determined at least in partbased on a timing. In some implementations, a timing is comprised of atiming of a beacon interval. In some implementations, a timing iscomprised of a timing relative to when the packet is transmitted. Aprocessor such as DSP 220 of FIG. 2 could perform the determinationcarried out at block 2002, although a person of ordinary skill in theart will appreciate that block 2002 can be implemented by another devicedescribed herein, or any other suitable device.

Next, at block 2004, a packet is scrambled based on the scrambler seeddetermined in block 2002. A processor such as DSP 220 of FIG. 2 couldperform the scrambling carried out at block 2004, although a person ofordinary skill in the art will appreciate that block 2004 can beimplemented by another device described herein, or any other suitabledevice.

Next, at block 2006, the scrambled packet is transmitted wirelessly. Atransmitter such as transmitter 210 of FIG. 2 could perform such afunction, although a person of ordinary skill in the art will appreciatethat block 2006 can be implemented by another device described herein,or any other suitable device.

FIG. 21 shows a flow chart of yet another exemplary method 2100 that maybe employed within the wireless device of FIG. 2. The method 2100 can beimplemented in whole or in part by the devices described herein, such asthe wireless device 202 shown in FIG. 2. FIG. 21 may be performed ateither AP 104 or STAs 106. Although the illustrated method 2100 isdescribed herein with reference to the wireless communication system 100discussed above with respect to FIG. 1, and the wireless device 202discussed in FIG. 2, a person having ordinary skill in the art willappreciate that the illustrated method 2100 can be implemented byanother device described herein, or any other suitable device. Althoughthe illustrated method 2100 is described herein with reference to aparticular order, in various implementations, blocks herein may beperformed in a different order, or omitted, and additional blocks may beadded.

First, at block 2102, a scrambled packet is wirelessly received. Areceiver such as receiver 212 of FIG. 2 could perform such a function,although a person of ordinary skill in the art will appreciate thatblock 2102 can be implemented by another device described herein, or anyother suitable device.

Next, at block 2104, a descrambler seed is determined at least in partbased on a timing. In some implementations, a timing is comprised of atiming of a beacon interval. In some implementations, a timing iscomprised of a timing relative to when the packet is transmitted. Aprocessor such as DSP 220 of FIG. 2 could perform the determinationcarried out at block 2104, although a person of ordinary skill in theart will appreciate that block 2104 can be implemented by another devicedescribed herein, or any other suitable device.

Next, at block 2106, the scrambled packet is descrambled based on thedescrambler seed determined in block 2104. A processor such as DSP 220of FIG. 2 could perform the descrambling carried out at block 2106,although a person of ordinary skill in the art will appreciate thatblock 2106 can be implemented by another device described herein, or anyother suitable device.

As used herein, the term “determining” encompasses a wide variety ofactions. For example, “determining” may include calculating, computing,processing, deriving, investigating, looking up (e.g., looking up in atable, a database or another data structure), ascertaining and the like.Also, “determining” may include receiving (e.g., receiving information),accessing (e.g., accessing data in a memory) and the like. Also,“determining” may include resolving, selecting, choosing, establishingand the like. Further, a “channel width” as used herein may encompass ormay also be referred to as a bandwidth in certain aspects.

As used herein, a phrase referring to “at least one of” a list of itemsrefers to any combination of those items, including single members. Asan example, “at least one of: a, b, or c” is intended to cover: a, b, c,a-b, a-c, b-c, and a-b-c.

The various operations of methods described above may be performed byany suitable means capable of performing the operations, such as varioushardware and/or software component(s), circuits, and/or module(s).Generally, any operations illustrated in the Figures may be performed bycorresponding functional means capable of performing the operations.

The various illustrative logical blocks, modules and circuits describedin connection with the present disclosure may be implemented orperformed with a general purpose processor, a digital signal processor(DSP), an application specific integrated circuit (ASIC), a fieldprogrammable gate array signal (FPGA) or other programmable logic device(PLD), discrete gate or transistor logic, discrete hardware componentsor any combination thereof designed to perform the functions describedherein. A general purpose processor may be a microprocessor, but in thealternative, the processor may be any commercially available processor,controller, microcontroller or state machine. A processor may also beimplemented as a combination of computing devices, e.g., a combinationof a DSP and a microprocessor, a plurality of microprocessors, one ormore microprocessors in conjunction with a DSP core, or any other suchconfiguration.

In one or more aspects, the functions described may be implemented inhardware, software, firmware, or any combination thereof. If implementedin software, the functions may be stored on or transmitted over as oneor more instructions or code on a computer-readable medium.Computer-readable media includes both computer storage media andcommunication media including any medium that facilitates transfer of acomputer program from one place to another. A storage media may be anyavailable media that can be accessed by a computer. By way of example,and not limitation, such computer-readable media can comprise RAM, ROM,EEPROM, CD-ROM or other optical disk storage, magnetic disk storage orother magnetic storage devices, or any other medium that can be used tocarry or store desired program code in the form of instructions or datastructures and that can be accessed by a computer. Also, any connectionis properly termed a computer-readable medium. For example, if thesoftware is transmitted from a web site, server, or other remote sourceusing a coaxial cable, fiber optic cable, twisted pair, digitalsubscriber line (DSL), or wireless technologies such as infrared, radio,and microwave, then the coaxial cable, fiber optic cable, twisted pair,DSL, or wireless technologies such as infrared, radio, and microwave areincluded in the definition of medium. Disk and disc, as used herein,includes compact disc (CD), laser disc, optical disc, digital versatiledisc (DVD), floppy disk and blu-ray disc where disks usually reproducedata magnetically, while discs reproduce data optically with lasers.Thus, in some aspects computer readable medium may comprisenon-transitory computer readable medium (e.g., tangible media). Inaddition, in some aspects computer readable medium may comprisetransitory computer readable medium (e.g., a signal). Combinations ofthe above should also be included within the scope of computer-readablemedia.

The methods disclosed herein comprise one or more steps or actions forachieving the described method. The method steps and/or actions may beinterchanged with one another without departing from the scope of theclaims. In other words, unless a specific order of steps or actions isspecified, the order and/or use of specific steps and/or actions may bemodified without departing from the scope of the claims.

The functions described may be implemented in hardware, software,firmware or any combination thereof. If implemented in software, thefunctions may be stored as one or more instructions on acomputer-readable medium. A storage media may be any available mediathat can be accessed by a computer. By way of example, and notlimitation, such computer-readable media can comprise RAM, ROM, EEPROM,CD-ROM or other optical disk storage, magnetic disk storage or othermagnetic storage devices, or any other medium that can be used to carryor store desired program code in the form of instructions or datastructures and that can be accessed by a computer. Disk and disc, asused herein, include compact disc (CD), laser disc, optical disc,digital versatile disc (DVD), floppy disk, and Blu-ray® disc where disksusually reproduce data magnetically, while discs reproduce dataoptically with lasers.

Thus, certain aspects may comprise a computer program product forperforming the operations presented herein. For example, such a computerprogram product may comprise a computer readable medium havinginstructions stored (and/or encoded) thereon, the instructions beingexecutable by one or more processors to perform the operations describedherein. For certain aspects, the computer program product may includepackaging material.

Software or instructions may also be transmitted over a transmissionmedium. For example, if the software is transmitted from a web site,server, or other remote source using a coaxial cable, fiber optic cable,twisted pair, digital subscriber line (DSL), or wireless technologiessuch as infrared, radio, and microwave, then the coaxial cable, fiberoptic cable, twisted pair, DSL, or wireless technologies such asinfrared, radio, and microwave are included in the definition oftransmission medium.

Further, it should be appreciated that modules and/or other appropriatemeans for performing the methods and techniques described herein can bedownloaded and/or otherwise obtained by a user terminal and/or basestation as applicable. For example, such a device can be coupled to aserver to facilitate the transfer of means for performing the methodsdescribed herein. Alternatively, various methods described herein can beprovided via storage means (e.g., RAM, ROM, a physical storage mediumsuch as a compact disc (CD) or floppy disk, etc.), such that a userterminal and/or base station can obtain the various methods uponcoupling or providing the storage means to the device. Moreover, anyother suitable technique for providing the methods and techniquesdescribed herein to a device can be utilized.

It is to be understood that the claims are not limited to the preciseconfiguration and components illustrated above. Various modifications,changes and variations may be made in the arrangement, operation anddetails of the methods and apparatus described above without departingfrom the scope of the claims.

While the foregoing is directed to aspects of the present disclosure,other and further aspects of the disclosure may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

What is claimed is:
 1. A method for wireless communication, comprising:inserting a plurality of scrambler seeds into a data unit comprising aplurality of data portions comprising at least one media access controlprotocol data unit, the at least one media access control protocol dataunit including a delimiter field, and at least one of the plurality ofscrambler seeds being included in the delimiter field; scrambling eachdata portion at least in part based on the at least one of the pluralityof scrambler seeds; and transmitting, via a transmitting device, thedata unit.
 2. The method of claim 1, wherein the data portions comprisecode words.
 3. The method of claim 1, wherein at least one of thescrambler seeds is prepended to a media access control header of the atleast one media access control protocol data unit.
 4. The method ofclaim 1, wherein: multiple media access control protocol data units areaggregated into an aggregated media access control protocol data unit.5. The method of claim 1, wherein the at least one of the plurality ofscrambler seeds is inserted in reserved bits of the delimiter field. 6.The method of claim 1, wherein the at least one of the plurality ofscrambler seeds is inserted in a delimiter signature field of thedelimiter field.
 7. An apparatus for wireless communication, comprising:a processor configured to: insert a plurality of scrambler seeds into adata unit comprising a plurality of data portions comprising at leastone media access control protocol data unit, the at least one mediaaccess control protocol data unit including a delimiter field, and atleast one of the plurality of scrambler seeds being included in thedelimiter field; scramble each data portion at least in part based onthe at least one of the plurality of scrambler seeds; and a transmitterconfigured to transmit the data unit.
 8. The apparatus of claim 7,wherein the processor is configured to prepend at least one of thescrambler seeds to a media access control header of the at least onemedia access control protocol data unit.
 9. The apparatus of claim 7,wherein the processor is configured to: aggregate multiple media accesscontrol protocol data units into an aggregated media access controlprotocol data unit.
 10. The apparatus of claim 7, wherein the processoris configured to insert the at least one of the plurality of scramblerseeds in reserved bits of the delimiter field.
 11. The apparatus ofclaim 7, wherein the processor is configured to insert the at least oneof the plurality of scrambler seeds in a delimiter signature field ofthe delimiter field.
 12. A method for wireless communication,comprising: receiving, via a receiving device, a data unit comprising aplurality of data portions comprising at least one media access controlprotocol data unit, the at least one media access control protocol dataunit including a delimiter field; identifying a plurality of scramblerseeds in the data unit, at least one of the plurality of scrambler seedsbeing included in the delimiter field; and descrambling each dataportion at least in part based on the at least one of the plurality ofscrambler seeds.
 13. The method of claim 12, wherein the data portionscomprise code words.
 14. The method of claim 12, wherein at least one ofthe scrambler seeds is prepended to a media access control header of theat least one media access control protocol data unit.
 15. The method ofclaim 12, wherein: multiple media access control protocol data units areaggregated into an aggregated media access control protocol data unit.16. The method of claim 12, wherein the at least one of the plurality ofscrambler seeds is inserted in reserved bits of the delimiter field. 17.The method of claim 12, wherein the at least one of the plurality ofscrambler seeds is inserted in a delimiter signature field of thedelimiter field.
 18. An apparatus for wireless communication,comprising: a receiver configured to receive a data unit comprising aplurality of data portions comprising at least one media access controlprotocol data unit, the at least one media access control protocol dataunit including a delimiter field; a processor configured to: identify aplurality of scrambler seeds in the data unit, at least one of theplurality of scrambler seeds being included in the delimiter field; anddescramble each data portion based at least in part on the at least oneof the plurality of scrambler seeds.
 19. The apparatus of claim 18,wherein the processor is configured to process at least one of thescrambler seeds prepended to a media access control header of the atleast one media access control protocol data unit.
 20. The apparatus ofclaim 18, wherein the processor is configured to process: multiple mediaaccess control protocol data units aggregated into an aggregated mediaaccess control protocol data unit.
 21. The apparatus of claim 18,wherein the processor is configured to process the at least one of theplurality of scrambler seeds inserted in reserved bits of the delimiterfield.
 22. The apparatus of claim 18, wherein the processor isconfigured to process the at least one of the plurality of scramblerseeds inserted in a delimiter signature field of the delimiter field.